Tablet computer stand with near field coupling enhancement

ABSTRACT

A tablet stand is disclosed which incorporates a near field antenna configuration which couples to a near field antenna in the back of a tablet and provides a near field antenna coupling region for near field communication at the front of the tablet. The stand may be completely passive and use conductive antenna elements and passive resonance matching circuit elements to provide efficient coupling. In another aspect a thin profile passive keyboard adapted for use with a near field enabled tablet is provided. In another aspect a mounting bracket or holder, embedded antenna, and passive keyboard combination is provided adapted for converting a tablet into a notebook type configuration.

RELATED APPLICATION INFORMATION

The present application is a continuation of application Ser. No.15/040,992 filed Feb. 10, 2016 which is a divisional application ofapplication Ser. No. 13/888,217 filed May 6, 2013 which claims priorityunder 35 U.S.C. Section 119(e) to U.S. Provisional Patent ApplicationSer. No. 61/643,132 filed May 4, 2012, the disclosures of which areincorporated herein by reference in their entirety.

BACKGROUND OF THE INVENTION

Tablet computers typically have a majority of surface area devoted to atouch screen of some type while having different form factors, screensizes and boundary regions around the screen. At the same time multiplewireless communication capabilities are desired with related antennasincorporated into the tablet structure. One such communicationcapability of interest is near field communication for short rangecommunication using inductive or magnetic coupling. Depending on thespecific tablet design and near field antenna design it may be necessaryor convenient to place the near field antenna at the back of the tablet.Due to the short range nature of near field communication and dependingon the material employed in the tablet screen and specific antennalocation, near field communication may require bringing the object to becommunicated with to the back of the tablet adjacent the near fieldantenna. While this may be perfectly acceptable during normal handhelduse it may become problematic when the tablet is placed in a stand.Also, communicating with devices adapted for front side use may beimpossible.

SUMMARY OF THE INVENTION

In a first aspect the present invention provides a stand for a portabledevice having a near field communication capability and antenna. Thestand comprises a first section having a device support surface adaptedto receive a back portion of the portable device, the first sectionhaving a first portion of a passive near field communication antenna, asecond section having a second portion of the passive near fieldcommunication antenna, and a third section connected to the first orsecond section. The sections are configurable to form a standconfiguration having an angled side view with an angled device supportsurface.

In another aspect the present invention provides a stand for a portabledevice having a near field communication capability and antenna,comprising a stand section having an angled device support surfaceadapted to receive a back portion of the portable device and a movablesection configurable from a position behind the support surface of thestand section to a position extending beyond the front of the supportsurface and having a passive near field communication antenna adapted toresonantly couple to the portable device antenna.

In another aspect the present invention provides a keyboard adapted fornear field communication, comprising a metallic substrate portionadapted to support thin profile keys, a keyboard near fieldcommunication antenna, and a ferrite material forming part of thekeyboard near field communication antenna or configured adjacentthereto.

Further aspects the present invention are described in the followingsections.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of a tablet mounted in a stand in an embodiment ofthe invention.

FIG. 2A is a front perspective view and FIG. 2B is a back view of astand and tablet combination in an embodiment of the invention.

FIG. 3 is a top view of the stand shown with the sections folded into aflat configuration in an embodiment of the invention.

FIGS. 4A and 4B illustrate different stand antenna configurations anddimensions in embodiments of the invention.

FIGS. 5A and 5B are side views of a tablet and stand in differentconfigurations with a keyboard adapted for wireless near fieldcommunication with the tablet in an embodiment of the invention.

FIGS. 6A and 6B are side and front perspective views, respectively, ofan alternative embodiment with a hinged bracket assembly, shown engagedwith a tablet and keyboard adapted for wireless near fieldcommunication.

FIG. 7 is a schematic drawing of a transmission line coupling twoantennas adapted for wireless near field communication.

FIG. 8 is a schematic drawing of two sections of a stand with anembedded transmission line coupling two antennas adapted for wirelessnear field communication in one embodiment of the invention.

FIG. 9 is a top schematic drawing of a keyboard having a metal substratefor supporting thin profile keys and adapted for wireless near fieldcommunication in one embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

In a first aspect a tablet stand is provided which incorporates a nearfield antenna configuration which couples to a near field antenna in theback of a tablet and provides a near field antenna coupling region fornear field communication at the front of the tablet. The stand may becompletely passive and use conductive antenna elements and passiveresonance matching circuit elements to provide efficient coupling. Inanother aspect a tablet stand and passive keyboard combination adaptedfor use with a near field enabled tablet is provided. In another aspecta rotatable mounting bracket with embedded antenna, near field enabledtablet, and passive keyboard combination is provided adapted forconverting the tablet into a notebook type configuration.

Referring to FIG. 1 a combination 10 of a tablet 12 mounted in stand 14is shown in a side view. Stand 14 as shown has three sections 16, 18,20. Section 18 supports the tablet at a desired angle which may beadjustable. Sections 16, 18, 20 may preferably be a single piececonstruction, for example of plastic, with bendable connections 24, 25between each section. This allows the stand to be folded flat forcompact storage when traveling and/or dimensioned to be a cover fortablet 12. If used as a cover the stand may include means to attach tothe tablet front, such as magnets or snap fit edges or edge portions(such as holders 26 illustrated below) or other known connection meansallowing easy removal of the cover/stand. Bendable connection 24 allowssection 16 to be reconfigured from a first position 22 indicated by thedashed line when near field communication is not needed to a secondposition in front of the tablet for near field communication at thefront of the tablet, as shown by the solid line. Alternatively, however,if portability is not critical the sections 16, 18, 20 may be formed ofa single solid piece, or only two pieces with section 16 pivotable aboutposition 24 to provide a more solid base and allow the reconfigurationnoted above. Also, more than three sections may be provided, forexample, four sections may be provided with section 22 being a fourthsection for stability and section 16 reconfigurable on top or belowsection 22 or 18, when in its first position. One or more of sectionjoining positions 24, 25, 27 may be separable so the sections there aremovable, not merely bendable, to adjust the stand configuration andtablet support angle. (The part of position 24 joining sections 16 and18, however, is not separable unless provisions are made for couplingthe embedded antenna across the separation, or through an additionalsection 22 via a transmission line, as discussed below. Also, in such anembodiment sections 22 and 16 may be a single piece with section 18movable to adjust the stand angle.) Separable joining positions mayinclude means to hold the sections in place, including recesses,magnets, snap fit or other means. Tablet 12 may rest against the standor may be held in position by a holder 26 which may have a shape(including a shape extending around the tablet edge in a U shape to forma slot for the tablet edge or a snap fit design) and extension fordesired stability. Alternatively, other means such as magnets may beemployed to hold the tablet in place. The relative size of the sectionsmay be varied and, for example, section 16 may be smaller (in lengthand/or in width).

FIG. 2A is a front perspective view and FIG. 2B is a back view of standand tablet combination 10. Shown in dashed lines in FIG. 2B is aschematic outline of the tablet near field communication antenna 28.Tablet 12 will also include appropriately designed near field readercircuitry. Antenna 28 may be any of various designs and may be a coil,for example and designed for resonance coupling at the near fieldcommunication frequency employed. For example, 13.56 MHz is commonlyemployed for near field communication using the ISO 14443 standard butvarious other frequencies and near field communication approaches arepossible. Dimensions of antenna 28 may vary as well as shape so theshape and size shown is schematic in nature and for illustrationpurposes. As shown section 18 is configured to overlap with the antenna28 position in the tablet. If the antenna 28 is configured at or nearthe top of device 12 section 18 will therefore extend up to the top ofthe back of the device or alternatively an additional section of thestand may be provided in this upper area, which is movably coupled tosection 18. In such case an embodiment of antenna 30 with two separatenear field inductive coupling portions connected by a transmission line,as described below in relation to FIG. 7 and FIG. 8 may be preferred formore efficient coupling. This transmission line may pass through thesections necessary to provide coupling at the desired position displacedfrom antenna 28, depending on the specific stand configuration.

Referring to FIG. 3 the stand 14 is shown in a top view assuming thesections may fold into a flat configuration as described above. If notthe view may be still generally be considered a top view (with relativedimensions and orientations altered accordingly) without affecting thegeneral functional discussion. As shown by the dashed line a passivenear field coupling antenna 30 is embedded in the stand sections 16 and18. Antenna 30 may comprise a conductive coil printed or mounted on thesections or a suitable substrate to maintain a thin configuration forstand 14, especially for portable applications. A tuning circuit 32 isprovided to match the resonant frequency to that of antenna 28 with oneor more passive elements including a capacitor to form a resonant tankcircuit along with the intrinsic antenna inductance. Design of theantenna for most effective coupling to antenna 28 may employ known nearfield antenna design teachings, such as in “The RFID Handbook”, by KlausFinkenzeller, 3^(rd) Ed., Wiley Publishing, 2010, the disclosure ofwhich is incorporated herein by reference. As will be appreciated fromFIG. 2B and FIG. 3 the near field coupling antenna 30 will efficientlycouple to the magnetic field from tablet antenna 28 and will preferablyencircle the entire diameter of antenna 28 to capture substantially allthe flux therefrom. The portion of antenna 30 on the front section 16 inturn will provide an efficient near field coupling area in front of thetablet. The antenna 30 area in section 16 and the antenna area insection 18, may be varied. For example, as shown in FIGS. 4A and 4B theantenna configuration in section 18 may be chosen to match the size ofantenna 28 while the antenna size in section 16 may be varied up tosubstantially full width of section 16 as shown. The antenna Q factor,antenna coupling factor, communication bandwidth and resonance tuningfrequency may be considered for optimizing the antenna parameters forthe application.

Although section 16 is shown extending in a front bottom portion of thesupport surface of stand section 18, which is desirable for coupling toa keyboard, in other embodiments where coupling to other portabledevices is desired, section 16 may extend to the side of the supportsurface to extend beyond the front of the tablet. Also, in such anembodiment section 16 may slide sideways into the stand section.Therefore, more generally, section 16 is movable in various ways alongwith near field coupling antenna 30 to extend the near field coupling tothe portable device to be accessible at the front of the stand.

Referring to FIG. 5A, tablet 12 and stand 14 are shown configured with akeyboard 40 adapted for wireless near field communication with tablet12. Keyboard 40 may employ the teachings of U.S. Pat. No. 7,006,014, thedisclosure of which is incorporated herein by reference. Keyboard 40will include one or more near field coupling antennas 42 which arecoupled to modulating circuitry in the keyboard to communicatekeystrokes to tablet 12, typically via load modulation detection inreader circuitry in tablet 12. Keyboard 40 preferably does not have abattery and the keyboard modulator circuitry is powered by the magneticfield from antenna 30. Separate antennas 42 may be provided forsimultaneously activated keyboard tags/modulators. For example, separaterow and column antennas may be provided which can be simultaneouslyindependently modulated at different sub-carrier frequencies to identifya key. Other examples are described in the '014 patent.

In the configuration shown in FIG. 5A antenna(s) 42 overlap portion ofantenna 30 in section 16 of the stand for good near field coupling viaantenna 30 to tablet antenna 28. (Means may be provided to hold thekeyboard in the stand 14 in this position if desired, for example, aside bracket on section 16, like bracket 26 described above, may beprovided.) If the keyboard has thin profile keys, in particular keyscommonly referred to as a scissor switch design, it may have a metallicsubstrate portion adapted for receiving the scissor switch keys 48, forexample, a thin aluminum substrate 44. This metallic substrate mayinterfere with the inductive near field coupling and a nonmetallicportion 45 may be provided and the keyboard near field communicationantenna 42 is configured over the nonmetallic portion 45. Non-scissorswitch keys 47, such as function keys may be provided in this area.Alternatively, a ferrite material 46 may be provided between keyboardnear field communication antenna 42 and the metallic substrate to reducenegative effects of the metal on the coupling. The ferrite material 46may be a separate layer or a coating or part of the antenna structure42. Also, while antenna 42 is shown above layer 44 it may be below thelayer 44 with layer 46 in between. FIG. 5A is therefore highly schematicas many different configurations may be provided. Also, if the ferritelayer is provided adjacent or on the antenna 42 it will increase theantenna inductance and coupling factor allowing a reduced antenna size.This may be desirable allowing a more compact implementation of theantenna(s) in the keyboard and providing more area for the keys. Theferrite will affect coupling parameters to antenna 30 and circuitry 32may be adjusted accordingly for desired communication. Keyboard 40,being wirelessly coupled, may be freely movable as shown in FIG. 5B witha representative distance D shown for illustration. Since tablet 12 hastypically a relatively small screen a communication distance ofcomfortable use may be provided (the drawing is not to scale forillustration purposes). An additional coupling antenna 43 may beprovided in keyboard 40 to enhance read range, as described in the '014patent. This antenna may be un-modulated by any direct key coupling andmay have different dimensions, Q factor and coupling factor than antenna42; therefore this antenna in combination with passive coupling antenna30 may thus enhance wireless near field communication with keyboard 40and tablet 12 over a distance otherwise impractical to implement.Although shown below antenna 42, antennas 42 and 43 may be in a side byside relation. Also, antenna 43 may have a ferrite material over some ora portion thereof if it overlaps metal layer 44. Also, the antenna 43may have a ferrite material and be relatively large while antenna(s) 42may not, for example, antenna(s) 42 may be of smaller size and notconfigured over metal layer 44. One illustrative embodiment is shown inFIG. 9 with a large antenna 43 partially overlapping metal substrate 44(preferably below substrate 44) and with partial ferrite layer 46 in theoverlap region. Also, shown are three smaller antennas 42 coupled to thekey modulated RFID tags as schematically shown by arrows 49. Threeantennas 42 may allow independent row, column and multi-function key tagconnections in an embodiment. Antenna(s) 42 may overlap antenna 43 asshown or may be beside antenna 43 as noted above. In an overlapconfiguration antenna 43 may enhance tag coupling parasitically whereasin a non-overlapping configuration a direct connection to the tag(s)power supply is preferably employed.

Referring to FIGS. 6A and 6B an alternative embodiment is shown withstand 14 replaced by a hinged bracket assembly 50, shown in side andfront perspective views engaged with a tablet 12 and keyboard 40. Therotatable mounting bracket 50, with embedded antenna 30, near fieldenabled tablet 12, and passive keyboard 40 combination as provided isadapted for easily converting the tablet into a notebook typeconfiguration. No direct electrical connections are required to tablet12 or keyboard 40 to convert the tablet into a notebook configuration,the two devices may simply be inserted into the two sides of mountingbracket 50.

Bracket assembly 50 may include two rotatably connected slotted sectionsadapted to receive tablet 12 and keyboard 40, respectively. For example,rotatable connection may be via hinges 52 fixed to one section (e.g.,bottom keyboard receiving section) and pivotably mounted to the othersection. Other hinge designs are possible, however. Near field couplingantenna 30 may be configured across the two sections through hinges 52.For example, the top and bottom portions of the antenna of FIG. 3 maypass through the respective hinges 52.

In an embodiment, bracket assembly 50 may be integrated with keyboard 40with a receptacle to receive tablet 12. In this case antenna(s) 42 (or43) and 30 need not be separate antennas. Also, the rotatable assemblymay be configured to rotate to a flat configuration aligned with theplane of the keyboard for portability. This flat configuration may befrom folding the assembly 50 toward the keyboard to the sides orrecesses therein, or to the front of the keyboard.

Alternatively coupling antenna 30 may comprise two antennas 30A and 30B,on the tablet receiving and keyboard receiving sections of bracket 50,respectively, which are coupled together. For example, as shown in FIG.7 a thin transmission line 60 may couple the two antennas 30A and 30B,through one of hinges 52. (Transmission line 60 may for example bedesigned to be 50 Ohms, but other designs are possible.) The coupling ofthe two antennas 30A and 30B to the transmission line is schematicallyshown provided by the inductor (loops) on the ends of the transmissionline. Coupling may be implemented in various ways to provide efficientcoupling and impedance matching.

Alternatively, the two antennas 30A and 30B may couple inductivelythrough adjacent positioning of respective edge portions of the antennacoils at the mating edge of bracket assembly 50 so that no wiring needpass through hinge 52. Also, inductive coupling may be provided at thehinges. Also, near field coupling antenna 30A or 30B within one or bothof hinges 52 may include a ferrite material to enhance coupling for asmaller coil geometry or if part of the hinge is composed of metal.Also, one hinge may include a ferrite material and coil and the otherhinge a non-ferrite coil. For example, the ferrite coil may couple toantenna 43 and the non-ferrite coil to antenna(s) 42. Also, in anembodiment the coil may wind about a ferrite cylinder shaped pieceforming part of the hinge spindle or axle.

It should be noted that a two antenna design 30A, 30B may also beprovided in the prior embodiments of stand 14 instead of a singleantenna design (with direct inductive coupling or via a strip line asillustrated in FIG. 7 and FIG. 8). This may prevent antenna damage dueto folding of the stand over time. Also, this may provide more efficientcoupling where one or both of antenna portions 30A, 30B are desired tobe smaller and spaced a distance apart.

The above embodiments are non-limiting and various modifications may befor specific implementations and such are within the scope of theinvention. Also, the drawings are not to scale and are not meant tolimit relative dimensions of illustrated components.

What is claimed is:
 1. A stand for a portable device having a near fieldcommunication capability and antenna, comprising: a first section; asecond section having a device support surface adapted to receive atleast a portion of the portable device, the second section having a nearfield coupling antenna; and a third section connected to the first orsecond section and wherein at least two of the sections are configurableto form a stand configuration having an angled side view with an angleddevice support surface.
 2. A stand for a portable device as set out inclaim 1, wherein the first, second and third sections are furtherreconfigurable to a flat configuration.
 3. A stand for a portable deviceas set out in claim 2, wherein one or more of the sections include meansto attach to the portable device in said flat configuration.
 4. A standfor a portable device as set out in claim 3, wherein said means toattach to the portable device comprises a magnet.
 5. A stand for aportable device as set out in claim 1, wherein the first section isreconfigurable from a first stand configuration wherein the firstsection is behind the portable device to a second stand configurationwherein the first section extends in front of the portable device.
 6. Astand for a portable device as set out in claim 1, wherein the firstsection comprises an electrical connection to said near field couplingantenna.
 7. A stand for a portable device as set out in claim 6, whereinthe electrical connection to said near field coupling antenna comprisesa transmission line.
 8. A stand for a portable device as set out inclaim 1, wherein the first section comprises a second portion of saidnear field coupling antenna.
 9. A stand for a portable device as set outin claim 1, wherein the first section is coupled to receive and transmitdata to and from the near field coupling antenna.